Boring tool

ABSTRACT

A boring tool for drilling relatively large diameter blind bottom holes in articles of solidified granular material such as sand molds or the like having a rotatable open frame including oppositely spaced spiraled side members interconnected by a material penetrating tip, and a continuous cutting edge marginally disposed along the tip and the side members and including material guiding ramps disposed inwardly of the cutting edge for assuring substantially complete discharge of separated granular material longitudinally outwardly from the tool.

United States Patent [19] Fischer et al.

[ BORING TOOL [75] Inventors: Carl E. Fischer; Albino F.

Delmastro; Thomas S. Burdge; l-larrel B. Brewington, all of Perkin;

. John B. Harris, East Peoria; Joseph Zaremba, Peoria, all of I11.

- [73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Nov. 15, 1972 [21] Appl. No.: 306,708

[52] US. Cl 175/409, 175/327, 175/394, 408/226, 408/230 [51] Int. Cl. E21c 13/00 [58] Field of Search 408/199, 207, 230, 226; 128/305; 175/394, 327, 409, 396

[56] References Cited UNITED STATES PATENTS 134,324 12/1872 Stouffer ..175/394X Apr. 16, 1974 7/1942 Malone ..408/226 3/1934 Vaughn ..175/327 Primary Examiner-Francis S. l-lusar Attorney, Agent, or Firm-Ralph E. Walters [57] ABSTRACT charge of separated granular material longitudinally outwardly from the tool.

9 Claims, 4 Drawing Figures BORING TOOL BACKGROUND OF THE INVENTION Forming holes in articles constructed of solidified granular material such as sand molds for manufacturing metal castings presents problems not adequately resolved by present cutters. For example, flat paddle-type cutters and spiraled augers are commonly used in conventional foundry operations to form pouring basins in sand molds. The flat paddle cutters leave residual sand on the bottom and sides of the hole, requiring subsequent laborious manual cleaning to prevent sand contamination of a casting formed by the mold. Spiraled auger cutters, although providing adequate lifting characteristics for removing material from the hole, forcibly throw sand particles by centrifugal action against the sides of the hole, thus eroding the basin wall. Eroded pouring basin side walls are susceptible to sloughing off during the pouring operation, thereby contaminating the casting. In addition, the cutting edges of such auger cutters generally exhibit poor wear characteristics. To offset the difficulty of sharpening or replacing the spiraled cutting edges, the cutters are generally fabricated from relatively costly alloys having more favorable wear properties. This practice increases the initial cost,

' further compounding the disadvantages of such cutters.

SUMMARY AND OBJECTS OF THE INVENTION Accordingly, it is an object of the present invention to provide an improved boring tool for drilling blind bottom holes in articles of solidified granular material such as sand molds or the like which is capable of producing a smooth substantially clean hole in such material.

Another object is to provide such an improved boring tool having a relatively lightweight open frame of long wearing construction which can be easily and conveniently releasably mounted on a conventional drill shank.

Another object is to provide a boring tool of the character described which has spaced self-sharpening cutting blades of spiraled configuration individually providing material discharge ramps for automatically substantially completely discharging separated material longitudinally upwardly and outwardly from the tool and the bore.

Other objects of this invention will become apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective side elevation of the boring tool of the present invention disposed within a blind bottom hole formed by the tool in a fragmentary sectioned portion of a sand casting mold.

FIG. 2 is a bottom view of the boring tool of the present invention illustrating the skewed relationship of the cutting tip with respect to the upper base.

FIG. 3 is an enlarged transverse cross section through one side of the frame of the boring tool of the present invention taken along the line III-III in FIG. 1.

FIG. 4 is an exploded perspective view of the boring tool of the present invention illustrating more clearly the drive coupling between the open blade frame and a drill shank.

DESCRIPTION or THE PREFERRED EMBODIMENT With particular reference to FIG. I of the drawings, a boring tool, as generally indicated by the reference numeral 10, is used for drilling a blind hole 12 in solidified granular material such as that employed in sand casting molds, one of which is fragmentarily represented and designated by the reference numeral 14. The boring tool has a tapered drill shank 16 with a key 18 and an internally threaded bore 20 formed on one end. A blade frame 22 of the boring tool is constructed in the form of an open quadrilateral to provide a relatively lightweight structure. The frame includes a base 24 with a keyway 26 formed therein to receive the shank key 18. The frame is attached to the shank by a capscrew 28 extending through a hole 30 formed in the base and into the threaded bore in the shank. As illustrated in FIG. 4, engagement of the key into the keyway provides a psoitive drive coupling between the shank and the blade frame.

The blade frame 22 further has an oppositely spaced pair of substantially axially extending spiraled side cutting edge members 32 and 34, each having a cutting edge 36 formed along their respective radially outwardly disposed margins. The fourth side of the open quadrilateral blade frame is formed by a flared cutting tip 38 transversely disposed in interconnecting relation between the bottom portion of the side members and is skewed approximately with respect to the base 24. As shown in FIGS. 1 and-2, the cutting edges 36 of the side members extend symmetrically inwardly in blending relation to the flared cutting tip to a center point 40.

As best shown in FIG. 3, the side members 32 and 34 as well as the cutting tip 38 have a similar cross section providing a wedge-shaped portion 42 defined by a pair of converging inner and outer planar surfaces 44 and 46 which intersect to form the cutting edge 36. A pair of relatively flat ramps 48 are individually formed inwardly of their respectively associated cutting edges 36 and extend radially outwardly from the center point 40 on opposite sides of the cutting tip. The ramps blendably extend upwardly therefrom on the side members and are individually bounded along the inside margin thereof by a shoulder 50, which along with the inner planar surface 44 form a pair of channular heliclined material guiding ramps 52 leading upwardly along the side members 32 and 34.

OPERATION While the operation of the present invention is clearly apparent from the foregoing description, further amplification will subsequently be made in the following brief summary of such operation.

The boring tool 10 is inserted into a suitable boring machine adapted for receiving the shank l6 and for rotating the blade 22 in the direction indicated by the arrows in FIGS. 1 and 2. Initially only the tip 38 engages the solidified granular material of the mold 14 which is sheared by the advancing cutting edges 36. Better penetration and lower thrust requirements are obtained, as compared to the previously described conventional cutters, due to the reltively narrow section at the center point 40. Separated material is directed radially out- .wardly and then upwardly along the channular heliclined ramps 52 and is subsequently discharged radially outwardly at the base 24. As the blade penetrates farther into the granular material, the cutting edges 36 around the tip and along the side members enlarge the initial cut and shape the hole to the desired configuration. Substantially all of the separated material is de posited onto the flat ramps 48 and is carried by the centrifugal force generated by rotation of the blade along the channular heliclined ramps 52 and discharged in the previously described manner at the base. Accordingly, a substantially clean, smooth bell-shaped blind hole 12 is produced by the boring tool of the present invention. It has been found that a hole having these characteristics forms a particularly advantageous pouring basin for receiving molten metal in a casting mold.

During the above-described operation, the abrasive action of the granular material of themold 14 on the wedge-shaped portion 42 produces substantially equal wear on the planar surfaces 44 and 46. The inwardly inclined angle of the surface 46, and particularly the predetermined radial clearance of the trailing portion thereof from the sides of the bored hole provide minimum drag as the tool wears. As the wedge portion is progressively worn away, the cutting edges 36 are maintained in a continuously sharpened condition for the operational life of the blade. Accordingly, the blade 22 is adapted to be cast from relatively inexpensive gray-iron material as compared to the more costly alloys employed in conventional tools which are required to be manually sharpened. Additional operational economies are realized .as a result of mounting the blade on the reusable shank 16 which may be fabricated from a scrap drill shank.

In view of the foregoing, it is readily apparent that the structure of the present invention provides an improved boring tool capable of drilling smooth substantially clean blind bottom holes in articles of solidified granular material such as sand molds or the like. It is further evident that this invention provides such an improved boring tool having a lightweight open frame of open blade frame for drilling blind bottom holes in so-v economical long wearing and self-sharpening construction which is releasably mounted on a replaceable drill shank.

Whilethe invention has been described and shown with particular reference to the preferred embodiment,

it will be apparent that variations might be possible that would fall within the scope of the present invention, which is not intended to be limited except as defined in the following claims.

What is claimed is:

1. A boring tool, for drilling blind bottom holes in solidified granular material and the like, comprising;

a rotatable open frame having oppositely spaced side members,

a material penetrating tip interconnecting said side members,

a continuous cutting edge marginally disposed along said tip and said side members, along an outer margin thereof, and

a channular ramp defined between said cutting edge and a shoulder extending along an inner margin of said tip and said side members including material retaining and guiding means formed along said tip and said side members inwardly of said cutting edge providing a path of movement for severed .material away from said cutting edge and longitudinally upwardly and outwardly from the tool without any appreciable droppage of such severed material radially inwardly of the frame during rotation of the tool.

2. The boring tool of claim 1 including a base integrally interconnecting said side members in oppositely spaced relation to said tip and including means for radially discharging said severed material outwardly of the tool.

3. The boring tool of claim 2 wherein said tip is skewed with respect to said base so that said channular ramp means on said side members form channular heliclines.

4. The boring tool of claim 1 wherein said tip and said side members include converging inner and outer planar surfaces forming wedge-shaped cross-section so that said cutting edge is substantially self-sharpening.

5. The boring tool of claim 4 wherein said outer planar surface is angularly inclined relative to the sides of such a blind bottom hole to minimize drag as the tool lidified granular material,

a. said frame including spaced spiraled side cutting edge means having predetermined top and bottom portions,

b. tip cutting edge means interconnecting the bottom portions of said side cutting edge means,

c. base means interconnecting the top portions of said side cutting edge means, and

d. material guiding ramp means formed inwardly of said side cutting edge means and said tip cutting edge means including a radially inwardly fdisposed continuous material retaining and guiding shoulder for assuring movement and discharge of separated granular material upwardly and radially outwardly from the base means of the tool without any appreciable droppage of such severed material radially inwardly of the frame during rotation of the tool.

8. The boring tool of claim 6 wherein said tip cutting.

edge means are skewed with respect to said base means so that said material guiding ramp means form channular heliclines along said side cutting edge means.

9. A boring tool, for drilling a blind bottom hole in solidified granular material, comprising; an integrally formed open quadrilateral blade frame including an upper base, a lower cutting tip having outwardly diverging marginally disposed cutting edges, a pair of oppositely spaced spiraled side members having outer marginal cutting edges axially extending between said base and said cutting tip, and a pair of material guiding ramps individually formed between said cutting edges on said side members and said tip and including a continuous inner marginally disposed material retaining and guiding shoulder inwardly spaced from said outer I marginal cutting edges of said side members and said tip for assuring movement and discharge of separated the frame during rotation of the tool. 

1. A boring tool, for drilling blind bottom holes in solidified granular material and the like, comprising; a rotatable open frame having oppositely spaced side members, a material penetrating tip interconnecting said side members, a continuous cutting edge marginally disposed along said tip and said side members, along an outer margin thereof, and a channular ramp defined between said cutting edge and a shoulder extending along an inner margin of said tip and said side members including material retaining and guiding means formed along said tip and said side members inwardly of said cutting edge providing a path of movement for severed material away from said cutting edge and longitudinally upwardly and outwardly from the tool without any appreciable droppage of such severed material radially inwardly of the frame during rotation of the tool.
 2. The boring tool of claim 1 including a base integrally interconnecting said side members in oppositely spaced relation to said tip and including means for radially discharging said severed material outwardly of the tool.
 3. The boring tool of claim 2 wherein said tip is skewed with respect to said base so that said channular ramp means on said side members form channular heliclines.
 4. The boring tool of claim 1 wherein said tip and said side members include converging inner and outer planar surfaces forming wedge-shaped cross-section so that said cutting edge is substantially self-sharpening.
 5. The boring tool of claim 4 wherein said outer planar surface is angularly inclined relative to the sides of such a blind bottom hole to minimize drag as the tool is rotated.
 6. A boring tool comprising an integrally formed open blade frame for drilling blind bottom holes in solidified granular material, a. said frame including spaced spiraled side cutting edge means having predetermined top and bottom portions, b. tip cutting edge means intErconnecting the bottom portions of said side cutting edge means, c. base means interconnecting the top portions of said side cutting edge means, and d. material guiding ramp means formed inwardly of said side cutting edge means and said tip cutting edge means including a radially inwardly disposed continuous material retaining and guiding shoulder for assuring movement and discharge of separated granular material upwardly and radially outwardly from the base means of the tool without any appreciable droppage of such severed material radially inwardly of the frame during rotation of the tool.
 7. The boring tool of claim 6 including an outwardly disposed wedge-shaped portion on said side cutting edge means and said tip cutting edge means so that said edge means are substantially self-sharpening as wear occurs during use.
 8. The boring tool of claim 6 wherein said tip cutting edge means are skewed with respect to said base means so that said material guiding ramp means form channular heliclines along said side cutting edge means.
 9. A boring tool, for drilling a blind bottom hole in solidified granular material, comprising; an integrally formed open quadrilateral blade frame including an upper base, a lower cutting tip having outwardly diverging marginally disposed cutting edges, a pair of oppositely spaced spiraled side members having outer marginal cutting edges axially extending between said base and said cutting tip, and a pair of material guiding ramps individually formed between said cutting edges on said side members and said tip and including a continuous inner marginally disposed material retaining and guiding shoulder inwardly spaced from said outer marginal cutting edges of said side members and said tip for assuring movement and discharge of separated granular material upwardly and radially outwardly from the upper base of the tool without any appreciable droppage of such severed material radially inwardly of the frame during rotation of the tool. 